The fragile Bitcoin economy will change drastically as companies scramble to obtain the proper licensing in response to guidance from the Financial Crimes Enforcement Network (FinCEN), which categorizes administrators and exchangers of virtual currencies as money services businesses.

FinCEN issued the guidance because "the industry and banks who provide services and law enforcement that investigate cases sought some regulatory certainty about where virtual currencies fall," says Steve Hudak, a spokesman for FinCEN.

FinCEN defines an exchanger as "a person engaged as a business in the exchange of virtual currency for real currency, funds or other virtual currency." An administrator is defined by FinCEN as "a person engaged as a business in issuing (putting into circulation) a virtual currency and who has the authority to redeem (to withdraw from circulation) such virtual currency."

"Those who are intermediaries in the transfer of virtual currencies from one person to another person, or to another location, are money transmitters that must register with FinCEN as MSBs,” says Jennifer Shasky Calvery, director of FinCEN, in a March 19 speech. “Some virtual currency exchangers are already registered with FinCEN as [money services businesses], though not necessarily as money transmitters."

"In some ways [the guidance] legitimizes the currency and in some ways it destroys it," says Bob Egan, founder and managing director at The Sepharim Group, in a phone interview.

To many, Bitcoin's appeal has been its unregulated, anonymous, cash-like nature. Adding regulation eliminates many of these traits.

Some companies that handle Bitcoin, such as CoinLab Inc. and BitInstant LLC, are already registered with FinCEN as money services businesses. As a result of the new FinCEN guidance, many more may have to do the same.

"What they did here is clever," says Charlie Shrem, co-founder and CEO of BitInstant, in an email. "They said, not only is a Bitcoin business an MSB, it is also a MTB (Money Transmitter); 48 states require separate MTB licensing."

The federal government requires only registration, reporting and recordkeeping from MSBs. But as MTBs, Bitcoin companies will also have to comply with the separate licensing practices.

State licensing looks like the biggest hurdle facing most Bitcoin companies now. Even mainstream payments providers such as Square Inc. have encountered pushback from state regulators over licensing.

Licensing is rarely available to new companies, says Shrem. "Many states only license 10 to 15 companies in the whole state," he says. "Specific states will need to make their own statement about this, but FinCEN has handed them a free pass here on defining Bitcoin for them."

Even if new entrants can obtain the proper licensing, the cost of doing so could exceed $10 million per company, Shrem says.

Many businesses which could be affected by future regulation and licensing rules will be unable to handle the costs, says Roman Shtylman, founder of Bitfloor, an exchange dealing in U.S. dollars. "Most business in the USD space can't even handle the regulations and costs."

"The whole idea [behind Bitcoin] was to create a freewheeling global economy without regulatory burden and operating costs," says Egan.

But that isn't going to happen anymore.

"The Treasury is acknowledging that virtual currencies exist and they're not going to go away," Egan says. "It's saying, 'we're acknowledging this is a global problem and because we haven't thought this all the way through let's do what we do with any other kind of money."

Shrem says the Bitcoin community should have seen this coming and anyone who continued to ignore the legal framework is at their own fault. FinCEN has been working to clarify the guidance for a year, says Shrem.

Bitcoin companies transmitting or exchanging the virtual currency for traditional currencies should register with FinCEN now, Hudak says. The IRS examines businesses on FinCEN's behalf, he says. Hudak refused to comment on the timeline for any consequences for noncompliance.